Segmented airfoil design for guide wires

ABSTRACT

The present invention is an improved wind turbine comprising: a wind turbine wheel having a hub, a rim and a cable extending between the hub and the rim; a set of airfoils rotatably carried by the cable and disposed between the hub and the rim; a cinch attached to the cable and disposed between adjacent airfoils; and, an upturned section included in at least one airfoil in the set of airfoils and disposed at a trailing edge of the airfoil wherein each airfoil has a different angle of attack relative to an adjacent airfoil.

BACKGROUND OF THE INVENTION 1) Field of the Invention

The present invention relates to an improved segmented self-positioningwind turbine assembly having self-positioning airfoils for generatingelectricity in response to the movement of atmospheric wind.

2) Description of Related Art

Windmills have been used for many generations for the purpose of pumpingwater from the ground and for generating electricity. A basic advantageof the windmill is that it uses the power of atmospheric wind to rotatea wheel having radially extending blades. This rotary movement may beconverted into various useful purposes. For example, wind turbines inthe form of propellers mounted on towers have been placed in areas wheresteady winds are prevalent, and the wind turbines are used to generateelectricity. An electrical generator is usually positioned near the axisof rotation of the propellers, adding the weight of the generator to theupper portion of the mast of the assembly. The blades of theconventional large wind turbines are large and made of expensive rigidmaterial and are constructed to have the blades extend radially from acentral hub, with no extra support at the outer tips of the blades. Theconventional wind turbine blades rotate at a high rate of revolutionsand must withstand both the centrifugal forces generated by the fastrevolution of the blades and the cantilever bending forces applied tothe blades by the wind. Since the outer portions of the blades usuallymove at a very high velocity and are engaged by strong winds, the largerthe blades the stronger they must be and the more expensive they become.Thus, there is a practical limit as to the length and width of theblades.

Another wind turbine type has rigid propellers that appear to be rigidlymounted to circular perimeter rims that support the outer ends of thepropellers, as shown in U.S. Pat. Nos. 1,233,232 and 6,064,123. Rubbertires or other rotary objects are placed in positions to engage theouter rim so as to rotate the rubber tires, with the driven tiresrotating the rotor of a generator. Thus, the rotation of the windturbine is used to generate electricity. A disadvantage of the rigidpropeller design is its ability to handle the fact that the closer tothe tip or perimeter of the blade you get, the faster the blade ismoving through the air and so the greater the apparent wind angle is.Thus, the blade needs to be turned further at the tips than at the hubso that there is a twist along its length. The blade optimal angle ofattack is determined by apparent wind direction. The apparent winddirection changes as the speed of blade increases, even when a uniformwind velocity exists across the wind turbine swept area. Blades with atwist are more expensive to make. Traditional wind turbine bladesthemselves are also very expensive to maintain and replace.

One of the advantages of a turbine wheel with a perimeter rim is thatthe electrical generator(s) may be positioned at the rim at the lowerarc of rotation of the rim where the generators are closer to the groundor other low supporting surface to remove the weight of the generatorfrom the upper portion of the mast. Also, the position of the generatorat a rim of the turbine wheel gives more access for installation,maintenance, repair and replacement of the generator. However, if theperimeter rim of the wind turbine wobbles during operation, it may bedifficult to maintain the generator in proper alignment with the rim andit appears likely that stress between the generator and the turbinewheel will occur. Also, if multiple ones of the generators are placed inoperative locations about an arc of the rim of the turbine, thepotential problems caused by the wobbling rim appear likely to be moreprevalent.

Further, it is advantageous for the rim to be as circular as possible soto reduce vibrations and to maintain consistent contact with thegenerator. To assist with maintaining a circular rim, guide wires can beincluded to extend from the perimeter of the rim to the hub to supportthe rim. However, the guide wires can create drag and reduce the outputof the wind turbine. It would be advantageous to reduce this drag causedby the guide wires.

Accordingly, it is an object of the present invention to provide a windturbine that adjust the angle of attack top seek optimization of therotations energy of the wind turbine.

It is another object of the present invention to create a wind turbinewith a perimeter allowing a generator to be positioned along the lowerportion of the perimeter.

It is another object of the present invention to provide a wind turbinewith auto-adjusting twist to seek optimization in response to winddirection and speed.

It is another object of the present invention to reduce or eliminate theneed for complicated blade pitch control system and vanes on oneembodiment.

SUMMARY OF THE INVENTION

The above objectives are accomplished according to the present inventionby providing a wind turbine having a mast, hub, cables, and rimcomprising: a plurality of airfoils carried by one or more cables anddisposed between the hub and the rim; wherein each airfoil includes aleading edge and a trailing edge and is symmetrical along a bisect fromthe leading edge to the trailing edge; a vane attached to each airfoilhaving a shaft and fin so that the airfoil has an angle of attack in therange of 10° and 12°; wherein each airfoil has a slightly differentangle of attack relative to the adjacent airfoil on the cable. In oneembodiment, the camber line and the chord line are superimposed. Thechord length can be in the range of 5 inches to 10 inches in embodimentand about 7 inches in one embodiment.

The invention can include airfoils having a length along the directionof the cable of between 4 feet and 12 feet, in one embodiment. Sailetscan be attached to the rim that can extend between 6 feet and 12 feetfrom the exterior of the rim wherein the sailets can be fixed pitch orvariable pitch. Spacers can be included between each airfoil to preventthe airfoil from interfering with the adjacent airfoil. Each airfoil caninclude an end cap. A stop, such as a pin, can be included in eachairfoil to prevent the airfoil from rotating a predetermined amount suchash less than 90°. The airfoil can be made from high performance vinylester resin, 40% unidirectional fiberglass reinforcement, 17% continuousfiberglass mat, balance proprietary resin mixture, UV inhibitors, colorof choice, and a surfacing protection veil.

The invention can include a wind turbine wheel having a hub, a rim and acable extending between the hub and the rim; a set of airfoils rotatablycarried by the cable and disposed between the hub and the rim; a cinchattached to the cable and disposed between adjacent airfoils; and, anupturned section included in at least one airfoil in the set of airfoilsand disposed at a trailing edge of the airfoil wherein each airfoil hasa different angle of attack relative to an adjacent airfoil. An innercable can extend between a distal end of the hub and the rim; and, a setof inner airfoils can be carried by the inner cable. An outer cable canextend between a distal end of the hub and the rim; and, a set of outerairfoils can be carried by the outer cable.

The wind turbine can include a first airfoil adjacent to the hub havinga first length; a second airfoil adjacent to the rim having a secondlength; wherein the first length is less than the second length. Anintermediate airfoil can have a length between the first length and thesecond length. A spacer assembly can be disposed between adjacentairfoils. A resilient member can be included in the spacer assembly. Awasher can be included in the spacer assembly. The airfoils in the setof airfoils can have a length in a range of 2 feet to 12 feet. Theairfoils in the set of air foils can have a shortest airfoil having alength of about 2 feet with the remaining airfoils having lengthslonger. A vane can be attached to at least one airfoil in the set ofairfoils.

The airfoils can include material selected from the group consisting ofhigh performance vinyl ester resin, 40% unidirectional fiberglassreinforcement, 17% continuous fiberglass mat, resin mixture, UVinhibitors, pigments, surfacing coatings or any combination. The windturbine can include a generator having a generator wheel configured toengage the rim and disposed below the rim.

BRIEF DESCRIPTION OF THE DRAWINGS

The construction designed to carry out the invention will hereinafter bedescribed, together with other features thereof. The invention will bemore readily understood from a reading of the following specificationand by reference to the accompanying drawings forming a part thereof,wherein an example of the invention is shown and wherein:

FIG. 1 shows a rear view of aspects of the invention;

FIG. 2 is an elevated view of aspects of the invention;

FIG. 3 is a side perspective view of aspects of an airfoil;

FIG. 4 is a perspective view of aspects of an airfoil;

FIG. 5 shows a side view of aspects of the invention;

FIG. 6 shows a side view of aspects of the invention;

FIGS. 7A and 7B are top views of aspects of the invention;

FIG. 8A is an upward perspective view of aspects of the invention;

FIG. 8B is a downward perspective view of aspects of the invention; and,

FIG. 9 is a side view of aspects of the invention.

It will be understood by those skilled in the art that one or moreaspects of this invention can meet certain objectives, while one or moreother aspects can meet certain other objectives. Each objective may notapply equally, in all its respects, to every aspect of this invention.As such, the preceding objects can be viewed in the alternative withrespect to any one aspect of this invention. These and other objects andfeatures of the invention will become more fully apparent when thefollowing detailed description is read in conjunction with theaccompanying figures and examples. However, it is to be understood thatboth the foregoing summary of the invention and the following detaileddescription are of a preferred embodiment and not restrictive of theinvention or other alternate embodiments of the invention. Inparticular, while the invention is described herein with reference to anumber of specific embodiments, it will be appreciated that thedescription is illustrative of the invention and is not constructed aslimiting of the invention. Various modifications and applications mayoccur to those who are skilled in the art, without departing from thespirit and the scope of the invention, as described by the appendedclaims. Likewise, other objects, features, benefits and advantages ofthe present invention will be apparent from this summary and certainembodiments described below, and will be readily apparent to thoseskilled in the art. Such objects, features, benefits and advantages willbe apparent from the above in conjunction with the accompanyingexamples, data, figures and all reasonable inferences to be drawntherefrom, alone or with consideration of the references incorporatedherein.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

With reference to the drawings, the invention will now be described inmore detail. Unless defined otherwise, all technical and scientificterms used herein have the same meaning as commonly understood to one ofordinary skill in the art to which the presently disclosed subjectmatter belongs. Although any methods, devices, and materials similar orequivalent to those described herein can be used in the practice ortesting of the presently disclosed subject matter, representativemethods, devices, and materials are herein described.

Referring to FIGS. 1 and 2, a wind turbine 10 is shown having a mast 12.The wind turbine includes a rim 14 that has cables extending from therim to a hub 18. A plurality of airfoils 20 can be carried by cablesextending from the hub to the rim. In one embodiment, the wind turbinecan include 80 cables that can be 80 feet or more in length and madefrom ¾ inch steel. A plurality of airfoils can include an opening thatreceives the cable and allows the airfoil to be slidable attached to androtate about the cable. The opening can be circular, oval or othershape. Each airfoil on a cable can rotate independently of the otherairfoils. For example, airfoil 22 a can rotate about the cableindependently of airfoil 22 b. The airfoil can be of different lengthsalong a cable. For example, an airfoil disposed adjacent to the rim canhave a shorter length that one disposed adjacent to the rim. Whenrotating, the airfoils are moving through the air at differing speed,due to the fact that the distance traveled for one airfoil is along adifference circumferential path. This travel distance can be representedby the travel distance=2πr² where r is the distance of the airfoil fromthe hub. Because each airfoil can rotate about the cable independently,the angle of attack of each airfoil can decrease from the hub to therim. Further, the airfoil section can be longer at the rim than the hubas the angle of attack dies not change as much the farther the distancefrom the hub (e.g. r). The angle of attack can stay relative the samewhile the pitch of each airfoil can vary from hub to rim.

In operation, the rim can engage a generator wheel 24 of generator 26 sothat rotational energy from the rim can be transferred to the generatorwheel and therefore turn the generator to produce electricity.

Referring to FIG. 3, an example of a section of an airfoil 40 is shown.The airfoil can include a leading edge 28 and a trailing edge 30. Acable opening 32 can be included in the airfoil to receive the cable andallow the airfoil to rotate about the cable. A forward opening 34 can beincluded and have a generally pyramid cross section and reduce theweight of the airfoil. A rear opening 36 can be included having a teardrop cross section. In one embodiment, the airfoil is symmetrical alongbisect 38. In one embodiment, the trailing edge of the airfoil caninclude an upturned section 39 that can increase the camber lineresulting in a high lift coefficient producing more rotational speed forthe wind turbine. With this upturned section, the angle of attack can beless for the same amount of rotational force created. In one embodiment,the upturned section can be in the range of 5 degrees to 15 degrees.

Referring to FIG. 4, one embodiment of the airfoil can include an uppersurface 60 and a lower surface 62 having a cable opening 64 disposed ina space defined between the upper and the lower surface. Support ribs 66can be disposed between the upper and lower surface to provide supportand maintain the shaped of the airfoil. The cable opening can extendthrough one or more ribs. The end of the airfoil can be closed with anend cap 68. The ribs can include rib openings.

Referring to FIG. 5, one embodiment of the airfoil 40 is shown carriedby cable 16 so that the airfoil can rotate about the cable. A vane 42can be attached to the airfoil extending toward the trailing edge andinclude a shaft 44 and fin 46. When the air flow in a direction shown as48, the vane causes the leading edge to face the wind direction causingthe airfoil to rotate toward the optimal angle of attack. As thisconfiguration reacts to the relative wind direction, each airfoil alongthe cable may have a slightly different angle of attack providing anadvantageous configuration of the plurality of airfoils along the cable.In one embodiment, the achieved angle of attack is in the range of 9 to13 degrees. In one embodiment, the airfoil is in the range of 5 to 10inches in width, 1 to 2 inches at its thickest portion and 8 to 12 feetin length. In one embodiment, the shaft is about 2 feet. The vane can beincluded in the end cap and on one or both ends of the airfoil.

Referring to FIG. 6, a plurality of airfoils are shown carried by cable16 wherein each airfoil can independent rotate about the cable 16. Theairfoil can include an opening 32 (FIG. 2) that received the cables andattached the airfoil to the wind turbine. Given that each airfoil canhave a different angle of attack, the airfoil assembly 50 can act as ablade with a twist. As each airfoil can rotate independently to eachother, the airfoil assembly can result in a twist resulting from thetrue wind speed, a twist that is not possible with the transitionalsingle blade. Therefore, an airfoil can automatically adjust to changesin the relative positions of the wind when the cable opening 32 locationis placed between the leading edge and trailing edge allowing theairfoil to automatically position itself at an optimum angle of attackregardless of true wind or apparent wind direction.

Referring to FIG. 7A, several airfoils are shown with airfoil 52 a beingpositioned above airfoil 52 b which it in turn positioned over airfoil52 c. Given that the vanes position each airfoil with different anglesof attack, we see that α_(a)≠α_(b)≠α_(c) so that the assembly creates atwist along the length of the cable. In one embodiment, α_(a), α_(b),and α_(c) can all be positive relative to horizontal line 41. FIG. 5Bshows the plurality of the airfoils superimposed as they would be alongthe cable.

The invention can provide for automatic blade pitch control with noblade pitch drive system or software. The airfoil sections canautomatically adjust to the optimum 80-foot blade twist. The automaticblade twist can also adjust itself for the true wind speed which currentblades cannot do. Maintenance will be significantly less than what isrequired with the traditional designs. Completely changing an airfoilassembly will take significantly less time than current blade exchanges.Transportation of the wind turbine is simplified with a much morecompact and simpler design that with the traditional blade systems. Whenparked, the airfoil assembly can accommodate higher wind than thetraditional blade designs. When the wind turbine is parked, the airfoilassembly will provide no lift as the wind can automatically turns thewheel downwind from the mast since the airfoils can be configured sothey can only rotate 90°. The vane can be fixed to the airfoil, so italways keeps airfoil at an ideal angle of attack eliminating a bladepitch drive. When the capacity of the generator is reached, and the windspeed increases the electric output can be limited by yawing out ofperpendicular to the sailets.

Referring to FIGS. 8A and 8B, the mast 12 supporting the wind turbinesupport the hub. Cables extending between the hub and the rim 14 asshown carrying a plurality of airfoils. An inner set of cables canextend from the proximal end of the hub 70 to rim 14. An outer set ofcables can extend from the distal end of the hub 72 to rim 14. A cableof the inner set of cables can include a set of inner airfoils 74extending from the hub to the rim. An outer cable in the outer set ofcables can include an outer set of airfoils 76 extending from the hub tothe rim.

Referring to FIG. 9, the airfoil 40 is shown rotatable carried by cable16. An adjacent airfoil 80 is shown disposed closer to the hub withairfoil 40 disposed closer to the rim. When rotating, inertia forces dueto the rotation of the turbine wheel force the airfoil toward the rimaway from the hub. This force can cause adjacent airfoils to bindagainst each other and restrict the ability of the airfoil to rotatesabout the cable interfering with the airfoils ability to optimize theangle of attack. The airfoils can be separated from each other by gaps82 that are created by a spacer assembly 84. The spacer assembly can besecured to the cable and prevents the airfoil inwardly adjacent to thespacer assembly from applying pressure to the outwardly adjacentairfoil. The spacer assembly can include an inward washer 82 that caninclude lubricity, high temperature tolerance, UV resistance, salt waterresistance and crush resistance. In one embodiment, the lower washer canbe made from polytetrafluoroethylene (PTFE). A cinch 84 can be cansecured to a fixed position on the cable preventing the cinch fromsliding along the cable. In one embodiment, the cinch can include twocomponents that are placed on either side of the cable and securedtogether such as with screws that can extend through cinch openings 88.Therefore, when the lower adjacent airfoil 80 is force toward an upwardadjacent airfoil, the cinch and washer prevent the lower adjacentairfoil from contacting the upper adjacent airfoil and therefore canprevent the airfoils from binding. The spacer assembly can include anupper washer 86 disposed between the cinch and the upper adjacentairfoil so that when the turbine wheel is as rest, the upper airfoilcontacts the upper washer and not the cinch. In one embodiment, aresilient member such as a spring or other tensioned member can bedisposed between the cinch and the lower washer or the lower washer andlower airfoil.

Unless specifically stated, terms and phrases used in this document, andvariations thereof, unless otherwise expressly stated, should beconstrued as open ended as opposed to limiting. Likewise, a group ofitems linked with the conjunction “and” should not be read as requiringthat each and every one of those items be present in the grouping, butrather should be read as “and/or” unless expressly stated otherwise.Similarly, a group of items linked with the conjunction “or” should notbe read as requiring mutual exclusivity among that group, but rathershould also be read as “and/or” unless expressly stated otherwise.

Furthermore, although items, elements or components of the disclosuremay be described or claimed in the singular, the plural is contemplatedto be within the scope thereof unless limitation to the singular isexplicitly stated. The presence of broadening words and phrases such as“one or more,” “at least,” “but not limited to” or other like phrases insome instances shall not be read to mean that the narrower case isintended or required in instances where such broadening phrases may beabsent.

While the present subject matter has been described in detail withrespect to specific exemplary embodiments and methods thereof, it willbe appreciated that those skilled in the art, upon attaining anunderstanding of the foregoing may readily produce alterations to,variations of, and equivalents to such embodiments. Accordingly, thescope of the present disclosure is by way of example rather than by wayof limitation, and the subject disclosure does not preclude inclusion ofsuch modifications, variations and/or additions to the present subjectmatter as would be readily apparent to one of ordinary skill in the artusing the teachings disclosed herein.

What is claimed is:
 1. An improved wind turbine comprising: a windturbine wheel having a hub, a rim and a cable extending between the huband the rim; a set of airfoils rotatably carried by the cable anddisposed between the hub and the rim; a cinch attached to the cable anddisposed between adjacent airfoils; said airfoils having symmetricalconvex top and bottom surfaces with said top surface transitioning intoan upturned section defined by an upward slope of a surface contouralong a trailing edge portion of said top surface of said airfoilsrelative to a horizontal plane extending from a leading edge to atrailing edge, wherein said upturned section does not extend above aplane defined by an apex of the convex top surface, and wherein eachairfoil has a different angle of attack relative to an adjacent airfoil;and, a vane mounted directly to at least one of said airfoils, whereinsaid vane includes a shaft extending beyond said trailing edge of saidairfoil and a fin disposed at a distal end of said shaft, wherein saidvane causes rotation of said airfoil to an optimal angle of attackrelative to a wind direction.
 2. The improved wind turbine of claim 1including: an inner cable extending between a proximal end of the huband the rim; and, a set of inner airfoils carried by the inner cable. 3.The improved wind turbine of claim 2 including: an outer cable extendingbetween a distal end of the hub and the rim; and, a set of outerairfoils carried by the outer cable.
 4. The improved wind turbine ofclaim 1 including: a first airfoil adjacent to the hub having a firstlength; a second airfoil adjacent to the rim having a second length;and, wherein the first length is less than the second length.
 5. Theimproved wind turbine of claim 4 including an intermediate airfoilhaving a length between the first length and the second length.
 6. Theimproved wind turbine of claim 1 including a spacer assembly disposedbetween adjacent airfoils.
 7. The improved wind turbine of claim 6including a resilient member included in the spacer assembly.
 8. Theimproved wind turbine of claim 6 including a washer included in thespacer assembly.
 9. The improved wind turbine of claim 1 wherein anairfoil in the set of airfoils has a length in a range of 2 feet to 12feet.
 10. The improved wind turbine of claim 1 including sailetsattached to the rim extending from an exterior of the rim.
 11. Theimproved wind turbine of claim 10 wherein the sailets include a variablepitch.
 12. The improved wind turbine of claim 1 said airfoils includematerial selected from the group consisting of high performance vinylester resin, 40% unidirectional fiberglass reinforcement, 17% continuousfiberglass mat, resin mixture, UV inhibitors, pigments, surfacingcoatings and combinations thereof.
 13. The improved wind turbine ofclaim 1 including a cable opening defined in each airfoil in the set ofairfoils for receiving the cable.
 14. The improved wind turbine of claim1 including a generator having a generator wheel configured to engagethe rim and disposed below the rim.
 15. An improved wind turbinecomprising: a wind turbine wheel having a rim; a hub included in thewind turbine wheel having a proximal end and a distal end; an inner setof cables extending between the proximal end of the hub and the rim; aset of inner airfoils rotatably attached to the inner set of cables; anouter set of cables extending between the distal end of the hub and therim; a set of outer airfoils rotatably attached to the outer set ofcables; said airfoils having symmetrical convex top and bottom surfaceswith said top surface transitioning into an upturned section defined byan upward slope of a surface contour along a trailing edge portion ofsaid top surface of said airfoils relative to a horizontal planeextending from a leading edge to a trailing edge, wherein said upturnedsection does not extend above a plane defined by an apex of the convextop surface; and, a vane mounted directly to at least one of saidairfoils, wherein said vane includes a shaft extending beyond saidtrailing edge of said airfoil and a fin disposed at a distal end of saidshaft, wherein said vane causes rotation of said airfoil to an optimalangle of attack relative to a wind direction.
 16. The improved windturbine of claim 15 including a spacer assembly disposed betweenadjacent airfoils.
 17. The improved wind turbine of claim 16 including acinch included in the spacer assembly.
 18. An improved wind turbinecomprising: a wind turbine wheel having a rim and a hub; a set of cablesextending between the hub and the rim; a set of airfoils independentlyrotatably attached to the set of cables and extending between the rimand the hub; and, said airfoils having symmetrical convex top and bottomsurfaces with said top surface transitioning into an upturned sectiondefined by an upward slope of a surface contour along a trailing edgeportion of said top surface of said airfoils relative to a horizontalplane extending from a leading edge to a trailing edge, wherein saidupturned section does not extend above a plane defined by an apex of theconvex top surface; and, a vane mounted directly to at least one of saidairfoils, wherein said vane includes a shaft extending beyond saidtrailing edge of said airfoil and a fin disposed at a distal end of saidshaft, wherein said vane causes rotation of said airfoil to an optimalangle of attack relative to a wind direction.